Very weird problem - only certain folders and photos in gallery of A5 show up to be copied onto PC

I want to copy all the photos from my A5 2017 onto my PC to give the phone to my son. But only 2 folders out of about 20 show up on my PC to be copied, and then only about a quarter of the actual photos get copied. I have no SD card. I have tried Smart Switch, Kies 3, downloading automatically via windows, restarting all my devices, swopping usb cables, selecting the items in the folders and trying to make duplicate folders on my phone - even that is weird, only the same photos that show up on the PC get copied. trawling the internet. Am now at a total loss!

Welcome to Android Central! Are these photos that you've taken with the phone's Camera app? If so, they should all be in the /DCIM/Camera directory, unless you moved them around to other directories as a way of creating separate albums.

Does Windows Explorer have the Show Hidden Folders/Files option turned on?